Problem: Subtract.
Solution: There are many ways to solve this problem. Let's see two ways we can solve it. Place Value We can think in terms of tenths: $\begin{aligned} &\phantom{=}87.2-69.4\\\\ &=872\text{ tenths} - 694\text{ tenths}\\\\ &=178\text{ tenths}\\\\ &=17.8 \end{aligned}$ Place value table Let's line up the numbers by their decimal places. Tens Ones $.$ Tenths $8$ ${7}$ $.$ ${2}$ $6$ $9$ $.$ ${4}$ Now, let's subtract each place value column. Tens Ones $.$ Tenths $\overset{7}{\cancel{{8}}}$ $\overset{16}{\cancel{{7}}}$ $.$ $\overset{12}{\cancel{{2}}}$ $-$ ${6}$ ${9}$ $.$ ${4}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $\underline{~~~~}$ $1$ $7$ $.$ $8$ $17.8 = 87.2 - 69.4$